If you do not have variations to be selected by natural or sexual selection on their superior abilities to survive and reproduce successfully then nothing can be naturally selected against the immediate environment.
A stable ecosystem is characterized by having a continual input of energy from the sun. This is required in order to sustain or maintain a stable structure. Without proper supply of energy, life would not exist. Hope this answers the question.
Answer:
"The separation of twins conjoined at the head was a medical miricle , but the The story of the surgery that made Ben Carson famous — and itsIf things go badly it would be terrible for the young doctor's career,”
EnJoY ThE AnSwEr!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!